Research On The Supporting Capacity Of Polymer Sheet With Thin Spray-on Liners

Intelligent mine construction is the development goal of mining industry in our country.Traditional supporting method of anchor net is difficult to meet the need of intelligent mining construction.Thin Spray-on Liners(TSL)technology is a new type of roadway support surface technology.Compared with metal mesh support,it has the advantages of safety,efficiency,high mechanization and automation,and has great development potential.Reinforcing Polymeric Thin Spray-on Liners(RPTSL)materials and their bearing capacity were studied in this paper.Two materials(RPTSL1 and RPTSL2)were selected to test the compressive,shear and tensile properties.The results showed that RPTSL1 was better than RPTSL2 in compressive,tensile,ductility and other indexes,so RPTSL1 was selected as the subsequent research object.According to the RPTSL1 material viscosity,fluidity,atomization and other screening and customization of special thin spray machine,determine the spraying method and the use of the spray machine,which lays a foundation for the bearing performance,supporting effect and field test.TSL can improve the bearing capacity of coal rock mass by bonding with the surface surrounding rock.In this paper,the tensile and compressive properties of RPTSL1 after spraying with coal and rock samples are compared and analyzed by using standard rock mechanics experimental methods.The results show that the compressive strength of the coal samples after single and four sides of RPTSL1 coating is increased by 17.9 % and 31.3 %,and the tensile strength of single side coating is increased by 26.3 %.The compressive strength of single-and four-sided sprayed specimens of RPTSL1 increased by 5.7 % and 13.5 %,respectively,and the tensile strength of single-and four-sided sprayed specimens of RPTSL1 increased by 16.3 %.At the same time,the post-peak integrity of sprayed samples is obviously higher than that of non-sprayed samples.It is concluded that RPTSL1 can obviously improve the bearing performance of coal and rock mass,especially in the soft rock condition,which has a good application prospect.In order to further analyze the supporting role of RPTSL1,this study adopts the linear bearing test method commonly used in domestic and foreign TSL studies to analyze the role and influence of RPTSL1 under the conditions of small deformation and large deformation of surrounding rock.Similar materials with different strengths were used to simulate soft rock and hard rock roadway surrounding rock,and the test area was 1.2m×1.2m.Distributed optical fiber was used to monitor the deformation of samples at different positions,and the test results were compared with those of metal mesh support samples.The results show that the tensile strain and maximum normal displacement of the specimen surface increase with the increase of load,and the variation trend is similar to linear relationship.Under small deformation condition,the strain and maximum falling displacement of hanging net support sample are 3～4 times that of RPTSL1 support sample,and under large deformation condition,the strain and maximum falling displacement of hanging net support sample are 2～3 times that of RPTSL1 support sample.Field spraying tests were carried out using RPTSL1 material and custom thin spray machine.Firstly,spraying is carried out in the hanging area to test the working state and possible problems of the whole spraying system.Comparing the spraying area with the surrounding area,it is found that the thin spraying material greatly reduces the scattering of small rock mass,and has the function of rust prevention to the metal mesh.The results show that RPTSL1 has fast curing speed and can be sprayed immediately.Spraying operation is convenient and fast,saving time and effort than hanging net operation;After 15 days of spraying,small rock mass scattering and obvious large deformation did not appear in the spraying area.Field test verified the feasibility of engineering application of RPTSL1 material and supporting spraying equipment,which laid a foundation for subsequent research on optimization of spraying system,automatic control and coupling with anchor digger.There are 84 pictures,12 tables and 67 references in this paper.